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Hi,

Newbie here.

I live in the UK, have solar panels from when the tariffs were excellent, drive short journeys these days, may retire soon and have a driveway. Therefore due to slight remaining range anxiety I am thinking of a plug in hybrid as my first venture into the EV world and ideally would charge it during the day if there was enough sunlight.

It occurred to me that what would be really great would be a not-so-fast charger that limits charge current to the car to whatever excess my solar panels are producing, even if it takes a little longer to charge. I found the Zappi controller/charger which seems to be able to do that job.

Then it occurred to me that if I just use a regular domestic 240V 13A socket, which ordinarily would take 4-5h to charge up the battery, why could I not just fit an off the shelf remote controlled circuit breaker to that socket which turns it on and off according to, for example, the brightness of the sunlight?

As a bit of a geek, the electronics required to do that would be pretty easy to set up and the cost minimal. It would take a little "tuning" to get it right but should be perfectly possible. Would turning the domestic power socket on and off according to the sunlight intensity damage the battery or charge circuit in any way? I would put in some kind of time delay so it was not turning on and off every few seconds obviously.

Thanks in advance for any advice.
 

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Welcome John,

I have been trying to convert my in laws to this way of thinking. I have nothing else to add but I commend you for using your PV for free miles :)
 

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The problem with Solar PV charging an EV is that the minimum rate supported by the charging protocol is 6a, about 1.5kW. If the PV isn't producing that amount of power then then the remainder will be pulled from the grid. Using the portable EVSE to lower the power required helps (I did this myself for a while), but the portable EVSE isn't the safest long-term method of charging. Also, the EVSE might not be adjustable down to 6a; most run at about 10a. I'm not sure constantly flipping the power is a good idea either. A hard-wired chargepoint is definitely better. You can get them installed with a government grant for around £150. The Zappi costs a bit more, but it's a clever bit of kit, and can be adjusted to charge at the minimum rate. It will also automatically increase\decrease the charge rate depending on what the PV is generating. Plus, if you need an urgent charge, you can ramp it up to the full 7kW at the press of a button

I've had my Zappi for a couple of months now, and can highly recommend it.
 

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It would take a little "tuning" to get it right but should be perfectly possible. Would turning the domestic power socket on and off according to the sunlight intensity damage the battery or charge circuit in any way?
Your idea could badly damage a LEAF pack by repeatedly starting a charge on a full or nearly full pack. Kangoo Z.E. has a similar problem but I'm not sure if there is a warning in the manual.

Starting a charge on a LEAF 24 and 30 when the battery is already in a high state of charge will damage the battery.

The manual warns against starting a charge when the car is at or above 98% SOC. So does the warranty.
 

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The BMW 225xe I have has options to set the charging rate at max, reduced and low, and also automatic rate selection based on the charging cable imprinted value. That gives quite a bit of flexibility as to charging rate, and using the granny charger the low rate is a fixed 6 amps, and at that rate would take about 4 hours or so to charge its admittedly fairly small EV battery.

I can honestly recommend it as a vehicle for mainly short journeys, I can get a pure ev trip of up to 18 miles now the weather is warming up. I haven’t used in petrol at all this week and I have been out and about every day.

Longer trips are done in hybrid mode of course, but it and its near relation the 330e are good cars to drive with a surprising performance if you care to use it.
 

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Hi and welcome

Now I'm no tech wizard but would it not be better to have a battery connected to your solar panels do that the panels charge this battery as and when during the day? You could then give your car a constant charge once the battery is done?

Regards

Kam

Sent from my EML-L09 using Tapatalk
 

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The car depends on your budget and usage profile but from the limited description I would say full BEV would suit you better.

I am prone to tinker but although controlling a charger to switch off and on dependant on solar is easy enough I was reluctant to for various reasons.

I work shifts so just use the granny (which is 2700w on a Leaf) to slow charge and make the most of the solar. Leaf has no setting for reduced charging but other cars have or different chargers can also do it. But when you weigh up the figures involved it would take some payback.
 

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The cost of enough batteries to make a noticeable contribution to your Ev's battery will be huge. And those batteries will degrade over time. Max out your panels first - much more use to everyone! Rather then muck around with batteries, it's better to charge during the day using a Zappi which will adapt as much as is possible to solar variations, or use Eco 7 or similar if you charge overnight (assuming the extra cost of having 2 rates pays for itself).
 

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The cost of enough batteries to make a noticeable contribution to your Ev's battery will be huge. And those batteries will degrade over time. Max out your panels first - much more use to everyone! Rather then muck around with batteries, it's better to charge during the day using a Zappi which will adapt as much as is possible to solar variations, or use Eco 7 or similar if you charge overnight (assuming the extra cost of having 2 rates pays for itself).
Plus the conversion losses involved in storing the power in the battery, then getting it back out again. You might only get back 80-90% of what you put in
 

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................................... it's better to charge during the day using a Zappi which will adapt as much as is possible to solar variations,
A large number of people leave the house before sun-up and such advice is useless to them. Their only option with PV is to feed it in and then try to recoup some using a night tariff. As a long term alternative, a properly integrated battery bank offers an opportunity to gain maximum personal benefit from a home PV system. And it might even be possible to fill the car overnight entirely from that bank despite the car being miles from home during that PV gain.
 

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A large number of people leave the house before sun-up and such advice is useless to them. Their only option with PV is to feed it in and then try to recoup some using a night tariff. As a long term alternative, a properly integrated battery bank offers an opportunity to gain maximum personal benefit from a home PV system. And it might even be possible to fill the car overnight entirely from that bank despite the car being miles from home during that PV gain.
I agree, apart from using the home battery to charge the car. If you have a home battery (and the car is not at home during the day) it's better to charge the home battery from PV in the summer, and E7 in the winter. The car should be charged overnight from E7, not the home battery (home battery discharge should be disabled during E7 times).

The reason for this is a car battery can easily consume a whole home batteries capacity, causing a full home battery degradation cycle. It would cost more in home battery degradation than just charging the car directly from E7.

Charging the car from E7 means the home battery can run everything else outside of the E7 hours. Such as the following day when it's raining so the PV can't even run the house or you have a powercut (if your home battery can work in a powercut).

Edit: Of course, everyone circumstances are different. You need to measure and adjust as required.
 

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I agree, apart from using the home battery to charge the car. If you have a home battery (and the car is not at home during the day) it's better to charge the home battery from PV in the summer, and E7 in the winter. The car should be charged overnight from E7, not the home battery (home battery discharge should be disabled during E7 times).
I also agree with that to a point. Except that all electrons produced by the PV and added to a home pack could potentially be used by the home to boil a kettle at 9 am or top-up a car at 10 pm. As such it will be 'worth' whatever the tariff happens to be at the time of that withdrawal. Planning the use of a battery bank to avoid its own degradation or hanging on to the power in case of a rare grid outage would seem to be a bit anorak to me. The use of E7 to fill a bank that is then not used to its full capacity would seem to be wasting its full potential to time-shift energy costs.

I have neither PV or battery bank and my usage makes E7 more expensive than normal tariffs. If I had all three of these facilities I would use the PV to store at home and not send to FIT. I would then run the bank down for general home use, rather than use the grid, after sun-down. Then plug the car in - again using the battery store at whatever time I got home. If necessary, as the bank is discharged, start drawing from the grid - into E7 time if that's needed and leave the battery bank discharged so that it's capacity is fully available to gain the max from next day's solar activity. That way, all of the daily solar gain is used - at zero cost. The car is filled mostly at zero cost. And any excess at E7 tariff.

That would be my initial experiment during the summer when the best PV gain is available. In winter it would require a bit more fine tuning but the main principles would still apply in maximising input and discharge of the bank daily so that all solar gain is used daily for home or car use, at no cost, rather than lose over the difference between FIT and meter costs.
 

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I have PV but no home battery. I have looked into them but for most people they just aren't worth it (from a £ POV). You cannot save enough money to cover the cost of the battery while it's under warranty.
 

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I've just started looking into lower charge rates for the Leaf and there doesn't seem to be much info on how to do it. Everyone who asks the question about how to lower the charge rate is immediately bombarded with various reasons why not to. "It'll take days to charge, it's slow, why would you want to do it" etc. etc.

Everyone has a reason. I have an inverter that can supply a constant 4kw, however, my battery bank and panels can't. So until I upgrade them, I would like to be able to turn down the charge current and get at least a little bit of charging from what I have at the moment. With my granny charger connected to my inverter, it is drawing 52a from the battery bank. I would prefer that number to be a bit lower. Doing about 20 miles a day, I don't need to charge from empty to full every day, so anything I can get from the sun is a bonus.

So... How to make it happen? From what I've gathered, it's down to buying a Zappi or OpenEVSE but surely there's a cost effective way to "fool" or modify another EVSE to charge at a lower rate? I have a PodPoint 7kw charger on my wall and it turns itself down (or the car tells it to turn down) to 3.3kw for my Leaf, so is there a way to instruct it to turn down to 1.5kw?
 

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I have an EVSE that can do 6 or 10 amps. I understand that the instruction to the car on what current to take is in the form of the mark-space of a square wave on one of the pins.
 

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What make, model, size, colour, weight is it (just kidding about the last three)? If I had an EVSE that did 6a I'd be a happy bunny! :D
 

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One way to achieve this is to get a granny charger which lets you set the rate. Mine from evconnectors has run perfectly for 3 years now, and even protected itself from a car-socket short-circuit which blew up my Mainpine ECU in my wall charger! So I'm impressed wih the quality of this item. I can set it to 6, 8, or 10A, and change that on the fly using keypad on the front. Exactly what I've been up to this morning!

Another way is to use a Zappi, which I believe uses a current sensor on the house supply so it can work out whether you have enough power to charge super-fast (up to 32A) or you can set it to economy slow-charge more where it simply uses up whatever spare, exportable power is available.

The lowest charging rate supported by the standard is 6A, call it 1.5 kW here in UK. But I believe that the cars in USA can go down to 6A at 110V, so in theory it's possible to fit a transformer to a wall charger, which would allow charging down to about 750W ! But haven't heard of anyone desperate enough to try that over here!

Yet another is to build your own charger, probably based on Mainpine ECU, which would allow 6A up to 32A variable. There are kits available, but can't remember their names. Search this Forum for Mainpine will probably find you more info.
 
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